1. Technical Field of the Invention
The present invention relates to novel s-triazine compounds containing at least 2 specific para-aminobenzalmalonate substituents and to various cosmetic applications thereof.
The present invention also relates to photoprotective compositions comprising said s-triazine compounds comprising at least 2 grafted para-aminobenzalmalonate substituents as sunscreens active in the UV radiation region.
2. Description of Background and/or Related and/or Prior Art:
It is known that radiation with wavelengths of from 280 nm to 400 nm makes possible browning of the human epidermis and that radiation with wavelengths of from 280 to 320 nm, known under the name of UV-B radiation, causes erythemas and skin burns which may be harmful to the development of natural tanning.
It is also known that UV-A rays, with wavelengths of from 320 to 400 nm, which cause browning of the skin, are capable of causing a detrimental change in the latter, in particular in the case of sensitive skin and/or of skin continually exposed to solar radiation. UV-A rays cause, in particular, a loss of elasticity of the skin and the appearance of wrinkles, resulting in premature cutaneous aging. They promote the triggering of the erythemal reaction or accentuate this reaction in certain individuals and can even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, such as the retention of the natural elasticity of the skin, individuals increasingly desire to control the effect of UV-A radiation on their skin. The term “sun protection factor” is understood to mean the ratio of the irradiation time necessary to reach the erythemogenic threshold in the presence of the screening agent tested to the irradiation time necessary to reach the same threshold in the absence of screening agent.
It is therefore desirable to have available compounds capable of absorbing UV-A rays.
In addition to their power in screening out UV-A radiation, the desired photoprotective compounds must also exhibit good cosmetic properties, good solubility in conventional solvents and in particular in fatty substances, such as oils and fats, and also good resistance to water and to sweat (persistence) and a satisfactory photostability.
Particularly exemplary such compounds which have been recommended for this purpose are the s-triazine derivatives bearing benzalmalonate substituents, described in EP-0,507,691 assigned to the assignee hereof. However, these compounds possess a liposolubility and photochemical stability which are not yet entirely satisfactory.